1. Field of the Invention
The present invention relates to a method, an object moving on a carrier such as a belt conveyer is photosensed as a static image by a television camera upon the flash of a stroboscope. The video or image signal delivered from the television camera is used to judge the good or bad of the object. The stroboscope flash timing is synchronized with the vertical synchronizing signal of the image signal from the camera.
2. Description of the Prior Art
Systems that judge the good or bad of an inspected object by shape irregularities are known as pattern recognition systems. Such systems are mainly used to segregate defective objects which produce irregular shape or pattern among the many similar shaped objects by a manner that, for instance, such objects, which are transferred on belt conveyors or the like, are picked up by a television camera in the same direction and are taken as a static image by utilizing a stroboscope flash on the object, whereas such image signal from the television camera is processed to provide the above mentioned judgement.
FIG. 1 illustrates such a conventional system by block diagram, wherein a is a moving object, and the system comprises by a television camera b which photosenses the object a, a monitor or a signal processing section c, a stroboscope section or lamp d that is used to secure a static image of the moving object a for camera b, and an oscillator e to flash the stroboscope lamp d, by which the consecutively moving objects a are photosensed by camera b to produce a video or image signal which is processed at the monitor or the signal processing section c. However, in the illustrated conventional system, since the system does not contain any means for synchronizing the stroboscope flash timing with the television camera in spite of the fact that it is used to obtain a static image of the object a, it is difficult to take a matched timing for the image signal processing. For instance, when the stroboscope lamp d flashes on the way during the horizontal scanning of the television camera b, if the horizontal scanning is about around the midway of one field, the lower half image signal of object a is the first output from camera b, which is then followed by a second image signal by the upper horizontal scanning. Accordingly, some methods or means are necessary to recognize that these 2 image signals express one object a. To this end, for instance, a stroboscope flash timing control circuitry or the like becomes necessary and hence the stroboscope system becomes extremely complicated.